Thermally compliant heatshield

ABSTRACT

A heat shield comprising a sidewall portion, a top portion, and a plurality of flexible tabs attached to the sidewall portion is described herein, in accordance with various embodiments. The top portion may comprise an aperture. The sidewall portion may extend at an angle between 80 degrees and 100 degrees from the top portion. The sidewall portion may bound a hexagonal void. The flexible tab may comprise an angle between 80 degrees and 100 degrees. The flexible tab may be fixed to the sidewall portion, wherein the flexible tab is configured to be attached to a fitting.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and claims priority to, and thebenefit of U.S. patent application Ser. No. 14/793,457, entitled“THERMALLY COMPLIANT HEATSHIELD,” filed on Jul. 7, 2015, The '457Application is hereby incorporated by reference in its entirety for allpurposes.

FIELD

This disclosure relates to a gas turbine engine, and more particularlyto heat shields for oil tube fittings.

BACKGROUND

Engine oil tubes and fittings may be subjected to relatively hightemperatures. Once subjected to excessive heating, oil may undergocoking. Oil coking may cause solid oil deposits to form within oiltubes, causing undesirable effects such as blocked passageways andfilters.

SUMMARY

A heat shield is described herein, in accordance with variousembodiments. A heat shield may comprise a top portion, the top portioncomprising an aperture, a sidewall portion, the sidewall portionextending at an angle between 80 degrees and 100 degrees from the topportion, and a flexible tab. The flexible tab may comprise an anglebetween 80 degrees and 100 degrees. The flexible tab may be fixed to thesidewall portion. The flexible tab may be configured to be attached to afitting, wherein said flexible tab is configured to flex in response toat least one of an increase and decrease in temperature. The sidewallportion may bound a void. In various embodiments, the heat shield may beconfigured to at least partially encase the fitting. In variousembodiments, the heat shield may be configured to impede heat transferbetween the fitting and surrounding air. In various embodiments, thesidewall portion of the heat shield and the fitting may be separated bya gap. In various embodiments, the flexible tab may comprise anaperture, wherein the flexible tab is configured to be attached to thefitting via the aperture via at least one of a weld, solder, or braze.In various embodiments, the flexible tab may comprise an aperture,wherein the flexible tab is configured to be attached to the fitting viaa plug weld via the aperture. In various embodiments, the heat shieldmay comprise at least one of a nickel-chromium based alloy and astainless steel.

An assembly is described herein, in accordance with various embodiments.An assembly may include an oil tube, a fitting, wherein the fitting isconfigured to be attached to the oil tube, and a heat shield, whereinthe heat shield is configured to be attached to the fitting. The heatshield may comprise a top portion, the top portion comprising anaperture, a sidewall portion, the sidewall portion extending at an anglebetween 80 degrees and 100 degrees from the top portion, the sidewallportion bounding a void, and a flexible tab. The flexible tab maycomprise an angle between 80 degrees and 100 degrees. The flexible tabmay be fixed to the sidewall portion, wherein the flexible tab isconfigured to be attached to a fitting. In various embodiments, theflexible tab may be configured to flex in response to at least one of anincrease and decrease in temperature. In various embodiments, the heatshield may be configured to at least partially encase the fitting. Invarious embodiments, the heat shield may be configured to prevent heattransfer between the fitting and surrounding air. In variousembodiments, the sidewall portion and the fitting may be separated by agap. In various embodiments, the tube may be a dual wall tube comprisingan inner tube and an outer tube. In various embodiments, the sidewallportion may bound a hexagonal void. In various embodiments, the heatshield may be attached to the tube fitting via at least one of a plugweld and a fastener. In various embodiments, the heat shield may bemanufactured via a brake bending process. In various embodiments, theheat shield may comprise at least one of a nickel-chromium based alloyand a stainless steel.

A method of cooling a tube fitting is disclosed herein, in accordancewith various embodiments. The method of cooling a tube fitting mayinclude forming a heat shield via a brake bending process, and couplingthe heat shield to an outer surface of a tube fitting via a flexibletab, the heat shield at least partially encasing the tube fitting. Theheat shield may comprise a top portion, a sidewall portion, and aflexible tab. The flexible tab may comprise an angle between 80 and 100degrees. The flexible tab may be fixed to the sidewall portion. Invarious embodiments, the method may further comprise reflecting, by theheat shield, a heat wave away from the tube fitting. In variousembodiments, the sidewall portion of the heat shield may be configuredto be separated from the tube fitting by a gap.

Introducing a heat shield may prevent oil tube fittings from excessivelyheating, preventing oil coking.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example gas turbine engine, in accordance withvarious embodiments;

FIG. 2A illustrates a schematic view of an example mid-turbine frameassembly, in accordance with various embodiments;

FIG. 2B illustrates a schematic view of an oil tube fitting heat shieldassembly, in accordance with various embodiments;

FIG. 3A illustrates a perspective view of an oil tube fitting heatshield assembly, in accordance with various embodiments;

FIG. 3B illustrates a perspective view of an oil tube fitting heatshield, in accordance with various embodiments;

FIG. 4A illustrates a cross-section view of a heat shield attached to anoil tube fitting via a plug weld, in accordance with variousembodiments;

FIG. 4B illustrates a cross-section view of a heat shield attached to anoil tube fitting via a fastener, in accordance with various embodiments;and

FIG. 5 illustrates a method of cooling an oil tube fitting, inaccordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice theinventions, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this invention and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation. The scope of theinvention is defined by the appended claims. For example, the stepsrecited in any of the method or process descriptions may be executed inany order and are not necessarily limited to the order presented.Furthermore, any reference to singular includes plural embodiments, andany reference to more than one component or step may include a singularembodiment or step. Also, any reference to attached, fixed, connected orthe like may include permanent, removable, temporary, partial, fulland/or any other possible attachment option. Additionally, any referenceto without contact (or similar phrases) may also include reduced contactor minimal contact. Surface shading lines may be used throughout thefigures to denote different parts but not necessarily to denote the sameor different materials. In some cases, reference coordinates may bespecific to each figure.

As used herein, “aft” refers to the direction associated with the tail(e.g., the back end) of an aircraft, or generally, to the direction ofexhaust of the gas turbine. As used herein, “forward” refers to thedirection associated with the nose (e.g., the front end) of an aircraft,or generally, to the direction of flight or motion.

As used herein, “distal” refers to the direction radially outward, orgenerally, away from the axis of rotation of a turbine engine. As usedherein, “proximal” refers to a direction radially inward, or generally,towards the axis of rotation of a turbine engine.

In various embodiments and with reference to FIG. 1, a gas turbineengine 20 is provided. Gas turbine engine 20 may be a two-spool turbofanthat generally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mayinclude, for example, an augmenter section among other systems orfeatures. In operation, fan section 22 can drive air along a bypassflow-path B while compressor section 24 can drive air for compressionand communication into combustor section 26 then expansion throughturbine section 28. Although depicted as a turbofan gas turbine engine20 herein, it should be understood that the concepts described hereinare not limited to use with turbofans as the teachings may be applied toother types of gas turbine engines including three-spool architectures.

Gas turbine engine 20 may generally comprise a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A-A′ relative to an engine static structure 36 via oneor more bearing systems 38 (shown as bearing system 38-1 and bearingsystem 38-2). It should be understood that various bearing systems 38 atvarious locations may alternatively or additionally be provided,including for example, bearing system 38, bearing system 38-1, andbearing system 38-2.

Low speed spool 30 may generally comprise an inner shaft 40 thatinterconnects a fan 42, a low pressure (or first) compressor section 44(also referred to a low pressure compressor) and a low pressure (orfirst) turbine section 46. Inner shaft 40 may be connected to fan 42through a geared architecture 48 that can drive fan 42 at a lower speedthan low speed spool 30. Geared architecture 48 may comprise a gearassembly 60 enclosed within a gear housing 62. Gear assembly 60 couplesinner shaft 40 to a rotating fan structure. High speed spool 32 maycomprise an outer shaft 50 that interconnects a high pressure compressor52 (e.g., a second compressor section) and high pressure (or second)turbine section (“HPT”) 54. A combustor 56 may be located between highpressure compressor 52 and HPT 54. A mid-turbine frame 57 of enginestatic structure 36 may be located generally between HPT 54 and lowpressure turbine 46. Mid-turbine frame 57 may support one or morebearing systems 38 in turbine section 28. Inner shaft 40 and outer shaft50 may be concentric and rotate via bearing systems 38 about the enginecentral longitudinal axis A-A′, which is collinear with theirlongitudinal axes. As used herein, a “high pressure” compressor orturbine experiences a higher pressure than a corresponding “lowpressure” compressor or turbine.

The core airflow may be compressed by low pressure compressor 44 thenhigh pressure compressor 52, mixed and burned with fuel in combustor 56,then expanded over HPT 54 and low pressure turbine 46. Mid-turbine frame57 includes airfoils 59 which are in the core airflow path. Low pressureturbine 46 and HPT 54 rotationally drive the respective low speed spool30 and high speed spool 32 in response to the expansion.

Gas turbine engine 20 may be, for example, a high-bypass geared aircraftengine. In various embodiments, the bypass ratio of gas turbine engine20 may be greater than about six (6). In various embodiments, the bypassratio of gas turbine engine 20 may be greater than ten (10). In variousembodiments, geared architecture 48 may be an epicyclic gear train, suchas a star gear system (sun gear in meshing engagement with a pluralityof star gears supported by a carrier and in meshing engagement with aring gear) or other gear system. Geared architecture 48 may have a gearreduction ratio of greater than about 2.3 and low pressure turbine 46may have a pressure ratio that is greater than about 5. In variousembodiments, the bypass ratio of gas turbine engine 20 is greater thanabout ten (10:1). In various embodiments, the diameter of fan 42 may besignificantly larger than that of the low pressure compressor 44, andthe low pressure turbine 46 may have a pressure ratio that is greaterthan about (5:1). Low pressure turbine 46 pressure ratio may be measuredprior to inlet of low pressure turbine 46 as related to the pressure atthe outlet of low pressure turbine 46 prior to an exhaust nozzle. Itshould be understood, however, that the above parameters are exemplaryof various embodiments of a suitable geared architecture engine and thatthe present disclosure contemplates other gas turbine engines includingdirect drive turbofans.

In various embodiments, with reference to FIG. 2A, a mid-turbine frame(MTF) assembly is illustrated. An xyz coordinate axis is provided forease of illustration. MTF assembly 257 may include bearing compartment238, outer case 266, and inner case 268. MTF vane 259 may be locatedbetween inner case 268 and outer case 266. Oil tube fitting 212 may beattached to a portion of bearing compartment 238. Oil tube 206 mayextend between outer case 266 and oil tube fitting 212. Oil 214 may belocated within oil tube 206. Oil 214 may be used to lubricate at least aportion of bearing compartment 238. Oil tube 206 may be located at leastpartially within MTF vane 259. Sleeve 210 may encase at least a portionof oil tube 206. Oil tube fitting heat shield (also referred to hereinas heat shield) 202 may be located between MTF vane 259 and oil tubefitting 212, whereby at least a portion of oil tube fitting 212 islocated in the negative y-direction from heat shield 202 and at least aportion of MTF vane 259 is located in the positive y-direction from heatshield 202.

Hot exhaust may impinge on MTF vane 259 which may cause MTF vane 259 toincrease in temperature due to convective heat transfer from the hotexhaust. The hot exhaust may be in the range from about 800° F. (427°C.) to about 1000° F. (538° C.) in one embodiment. Heat waves 218 mayradiate from MTF vane 259. In various embodiments, heat waves mayradiate to other nearby components which may cause the nearby componentsto increase in temperature. In return, the nearby components maytransfer heat to other adjacent components and/or fluids. For example,heat waves may radiate from MTF vane 259 to oil tube 206 and mayconvectively transfer heat from MTF vane 259 to oil tube 206. Heat maybe conductively transferred to oil located inside oil tube 206.Furthermore, when oil exceeds various threshold temperatures, it mayundergo severe oxidative and thermal breakdown which may cause soliddeposits to form. These deposits may be undesirable as they may impedethe flow of fluid through various components including, for example,tubes and filters. Heat shield 202 may be configured to block heat waves218 radiating from MTF vane 259 from directly impinging on oil tubefitting 212. Furthermore, heat shield 202 may help minimize convectiveheat transfer from hot air surrounding oil tube fitting 212.Accordingly, heat shield 202 may prevent heat from being transferred tooil tube fitting 212. In various embodiments, heat shield 202 mayprevent oil from coking within oil tube fitting 212. Sleeve 210 may beconfigured to block radiating heat waves from MTF vane 259 fromimpinging on oil tube 206.

In various embodiments, with reference to FIG. 2B, oil tube 206 maycomprise an inner tube 207 and an outer tube 208. Accordingly, oil tube206 may be referred to as a dual wall tube. Inner tube 207 may beenclosed by outer tube 208. There may be a space between inner tube 207and outer tube 208 which may be occupied by air. The outer tube 208 maybe configured to contain oil within outer tube 208 in the event thatthere is an oil leak from inner tube 207. Outer tube 208 may beconfigured to prevent heat transfer from surrounding hot air to innertube 207. Oil tube 206 may be configured to attach to oil tube fitting212. Oil tube 206 may be attached to oil tube fitting 212 via weld,solder, braze, or any other suitable method. Heat shield 202 maycomprise a sidewall portion 204 and a top portion 203. Sidewall portion204 of heat shield 202 may be configured to at least partially encaseoil tube fitting 212. Top portion 203 of heat shield 202 may beconfigured to at least partially encase oil tube fitting 212.Accordingly, heat shield 202 may be configured to at least partiallyencase oil tube fitting 212. In various embodiments, sidewall portion204 may extend in a direction that is normal to top portion 203. Invarious embodiments, sidewall portion 204 may extend at an angle betweeneighty degrees and one hundred degrees (80°-100°) from top portion 203.Accordingly, sidewall portion 204 and top portion 203 may form an anglebetween eighty degrees and one hundred degrees (80°-100°).

In various embodiments, oil tube fitting 212 may be separated fromsidewall portion 204 of heat shield 202 by a gap 294. Heat shield 202may be configured to be attached to oil tube fitting 212 such that thereis a gap 294 between sidewall portion 204 of heat shield 202 and oiltube fitting 212. Sidewall portion 204 may be configured to be separatedfrom oil tube fitting 212 by gap 294 such that a conductive thermal pathdoes not exist between sidewall portion 204 and oil tube fitting 212.Gap 294 may be configured to be minimal while allowing thermal expansionof heat shield 202 and oil tube fitting 212 without creating a thermalconduction path between heat shield 202 and oil tube fitting 212. Invarious embodiments, gap 294 may comprise a distance in a range fromabout 0.1 millimeters to about 7 millimeters and in various embodiments,in a range from about 1 millimeter to about 4 millimeters and in variousembodiments, gap 294 may comprise a distance of about 2 millimeters.Minimizing gap 294 may allow heat shield 202 to more effectivelyminimize convective heat transfer between oil tube fitting 212 andsurrounding hot air. Minimizing gap 294 may allow heat shield 202 tomore effectively minimize convective heat transfer between oil tubefitting 212 and radiated heat from an adjacent MTF vane. Gap 294 may beconfigured to prevent a thermal conduction path between sidewall portion204 and oil tube fitting 212 during thermal expansion of oil tubefitting 212 and/or heat shield 202.

In various embodiments, various components of MTF assemblies maycomprise various materials. Various components, including heat shield202, may comprise a high temperature metal (e.g., an austeniticnickel-chromium-based alloy such as that available under the trade nameINCONEL), a high temperature composite, and/or the like. In variousembodiments, heat shield 202 may comprise a high temperature stainlesssteel (e.g., type 330 stainless steel).

With reference to FIG. 3A and FIG. 3B, elements with like elementnumbering as depicted in FIG. 2A and FIG. 2B, are intended to be thesame and will not be repeated for the sake of clarity.

In various embodiments, with reference to FIG. 2B and FIG. 3A, heatshield 202 may comprise flexible tab 206. Flexible tab 206 may be fixedto sidewall portion 204. Flexible tab 206 may comprise a right angle.Flexible tab 206 may comprise an angle between eighty degrees and onehundred degrees (80°-100°). The sidewall portion 204 of flexible tab 206may extend in a direction that is normal to the top portion 203 offlexible tab 206. Flexible tab 206 may comprise aperture 286. In variousembodiments, aperture 286 may be configured to accommodate a plug weld.In various embodiments, aperture 286 may be configured to accommodate afastener. In various embodiments, top portion 203 of heat shield 202 maycomprise aperture 316. Aperture 316 may be configured to allow fittingpost 314 to be located within aperture 316 when in the installedposition. Aperture 316 may be configured to be large enough to allowvarious components such as fittings attached to oil tube 206 to slidethrough aperture 316 in response to sliding heat shield 202 over oiltube 206 to an installed position.

In various embodiments, with reference to FIG. 3B, heat shield 202 maybe manufactured via a sheet metal brake bending process. In variousembodiments, a brake bending process may include a piece of sheet metalthat is cut into a desired shape via a two-axis laser, water jet, or thelike. Flexible tab 206, flexible tab 307, flexible tab 308, aperture286, aperture 316, and any other apertures or features may also be cutinto the sheet metal at this point. Next, the sheet metal may be bentalong a straight line several times until the desired shape is formed,resulting in heat shield 202. Finally, the newly formed edges, such asedge 322 for example, may be welded together, via weld 384 for example,to fill the gap that may exist between the newly formed edges ofsidewall portion 204. Accordingly, no gap

In various embodiments, with reference now to FIG. 2B, heat shield 202may comprise a wall thickness 292. In various embodiments, heat shield202 may be manufactured via a hydro-forming process. Wall thickness 292may be chosen according to various design considerations. In variousembodiments, wall thickness 292 may be between 0.010 in (0.25 mm) and0.030 in (0.76 mm) in thick. During manufacturing, sheet metal of apreferred wall thickness may be chosen to be hydro-formed to the desiredheat shield geometry. For example, if a heat shield comprising a wallthickness of 0.5 mm is desired, a piece of sheet metal comprising a wallthickness of 0.5 mm may be used and formed into the desired geometryusing high pressure hydraulic fluid to press the sheet metal into a diein a process known as hydro-forming. In various embodiments, a singlepiece of sheet metal may be hydro-formed into heat shield 202. Invarious embodiments, two or more pieces of sheet metal may behydro-formed into different geometries and welded together to form heatshield 202.

With reference now to FIG. 2B and FIG. 3A, heat shield 202 may furthercomprise flexible tab 307 and flexible tab 308, according to variousembodiments. Accordingly, heat shield 202 may comprise a plurality offlexible tabs. In various embodiments, flexible tab 307 and flexible tab308 may be similar to flexible tab 206. In various embodiments, oil tubefitting 212 may comprise a plurality of attachment posts, such asattachment post 216, for example. In various embodiments, flexible tab307 may be configured to be attached to attachment post 216. In variousembodiments, flexible tab 308 may be similar to flexible tab 307.Flexible tab 308 may be configured to be attached to an attachment postlocated adjacent to attachment post 216.

With reference to FIG. 4A and FIG. 4B, elements with like elementnumbering as depicted in FIG. 2A through FIG. 3B, are intended to be thesame and will not be repeated for the sake of clarity.

With reference now to FIG. 4A, flexible tab 206 may be configured toattach to oil tube fitting 212. In various embodiments, flexible tab 206may be configured to attach to oil tube fitting 212 via weld, solder,braze, or any other suitable method. In various embodiments, flexibletab 206 may be configured to attach to oil tube 206 via a plug weld 288.In various embodiments, flexible tab 206 may be attached to oil tubefitting 212, whereby a plug weld 288 is applied into aperture 286,thereby attaching flexible tab 206 to oil tube fitting 212.

With reference now to FIG. 4B, flexible tab 206 may be configured toattach to oil tube fitting 212 via a fastener 489, such as a screw or abolt for example. In various embodiments, fastener 489 may be insertedinto aperture 286 and threadingly attach to oil tube fitting 212,thereby attaching flexible tab 206 to oil tube fitting 212.

In various embodiments, with further reference to FIG. 2B and FIG. 3A,flexible tab 307 may be attached to oil tube fitting 212 via attachmentpost 216 in a similar manner as flexible tab 206. Flexible tab 308 maybe attached to oil tube fitting 212 in a similar manner as flexible tab307. In various embodiments, flexible tab 206, flexible tab 307, andflexible tab 308 may be configured to flex or bend relative to heatshield 202 during thermal expansion and/or contraction of oil tubefitting 212 and/or heat shield 202, thereby preventing heat shield 202from bending or distorting during such event. Accordingly, flexible tabs206, 307, and 308 may prevent heat shield 202 from cracking or breakingduring operation, thus preventing cooling efficiency of heat shield 202from decreasing during a thermal expansion and/or contraction event.Accordingly, flexible tabs 206, 307, and 308 may be configured to flexin response to an increase and/or decrease in temperature.

In various embodiments, the sidewall portion 204 of heat shield 202 maycomprise a hexagonal geometry. For example, FIG. 3B illustrates thesidewall portion 204 of heat shield 202, wherein the sidewall portion204 bounds a hexagonal void. In various embodiments, the sidewallportion 204 of heat shield 202 may comprise one of a square,rectangular, pentagon, heptagon, octagon, oblong, round, elliptical, orany other geometry. The geometry of the sidewall portion 204 of heatshield 202 may be driven by the geometry of oil tube fitting 212.Accordingly, the geometry of oil tube fitting 212 and sidewall portion204 may be complementary.

With reference to FIG. 5, a method 500 of cooling a tube fitting isdisclosed herein, in accordance with various embodiments. The method 500of cooling a tube fitting may include forming a heat shield in step 501.Step 502 may include coupling said heat shield to a tube fitting via aflexible tab. Step 503 may include reflecting, by the heat shield, aheat wave. With further reference to FIG. 2A and FIG. 3A, step 501 mayinclude forming heat shield 202 via the brake bending process asdescribed herein. Step 502 may include coupling heat shield 202 to anouter surface of oil tube fitting 212 via flexible tab 206, 307, and/or308. Heat shield 202 may at least partially encase oil tube fitting 212.Step 503 may include reflecting, by heat shield 202, a heat wave 218away from oil tube fitting 212.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the inventions. The scope of the inventions is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A heat shield comprising: a top portion, the topportion comprising an aperture; a sidewall portion, the sidewall portionextending at an angle between 80 and 100 degrees from the top portion,the sidewall portion bounding a void; and a flexible tab, the flexibletab comprising an angle between 80 and 100 degrees, the flexible tabbeing fixed to the sidewall portion, the flexible tab being configuredto be attached to a fitting, wherein said flexible tab is configured toflex in response to at least one of an increase and a decrease intemperature.
 2. The heat shield of claim 1, wherein the heat shield isconfigured to at least partially encase the fitting.
 3. The heat shieldof claim 2, wherein the heat shield is configured to impede heattransfer between the fitting and surrounding air.
 4. The heat shield ofclaim 3, wherein the sidewall portion of the heat shield and the fittingare separated by a gap.
 5. The heat shield of claim 1, wherein theflexible tab comprises an aperture, wherein the flexible tab isconfigured to be attached to the fitting via the aperture via at leastone of a weld, solder, or braze.
 6. The heat shield of claim 1, whereinthe flexible tab comprises an aperture, wherein the flexible tab isconfigured to be attached to the fitting via a plug weld via theaperture.
 7. The heat shield of claim 1, wherein the heat shieldcomprises at least one of a nickel-chromium based alloy or a stainlesssteel.
 8. The heat shield of claim 1, wherein the flexible tab is cutinto the top portion and the sidewall portion.